calibre

An e-book manager. It can view, convert, edit and catalog e-books in all of the major e-book formats. It can also talk to e-book reader devices. It can go out to the internet and fetch metadata for your books. It can download newspapers and convert them into e-books for convenient reading. It is cross platform, running on Linux, Windows and macOS.

Calibre supports many file formats and reading devices. Most e-book formats can be edited, for example, by changing the font, font size, margins, and metadata, and by adding an auto-generated table of contents. Conversion and editing are easily applied to appropriately licensed digital books, but commercially purchased e-books may need to have digital rights management (DRM) restrictions removed. Calibre does not natively support DRM removal, but may allow DRM removal after installing plug-ins with such a function.

Calibre allows users to sort and group e-books by metadata fields. Metadata can be pulled from many different sources, e.g., ISBNdb.com; online booksellers; and providers of free e-books and periodicals in the US and elsewhere, such as the Internet Archive, Munsey's Magazine, and Project Gutenberg; and social networking sites for readers, such as Goodreads and LibraryThing. It is possible to search the Calibre library by various fields, such as author, title, or keyword; however as of 2020, full-text search has not yet been implemented.

E-books can be imported into the Calibre library, either by sideloading files manually or by wirelessly syncing an e-book reading device with the cloud storage service in which the Calibre library is backed up, or with the computer on which Calibre resides. Also, online content can be harvested and converted to e-books. This conversion is facilitated by so-called recipes, short programs written in a Python-based domain-specific language. E-books can then be exported to all supported reading devices via USB, Calibre's integrated mail server, or wirelessly. Mailing e-books enables, for example, sending personal documents to the Amazon Kindle family of e-readers and tablet computers.

Calibre also contains an application to create and edit e-books directly, similar to the more full-featured Sigil application, but without the latter's WYSIWYG editing mode.

https://manual.calibre-ebook.com/ 

https://github.com/kovidgoyal/calibre 

https://en.wikipedia.org/wiki/Calibre_(software)